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Evaluation of building wrap

Martin, I don't recall ever seeing an evaluation of the various types of building wrap. Bits and pieces in various articles, but nothing comprehensive. If that's been done, please send me the link.

Otherwise, In our country, we've got Tyvek, some woven products and a bunch of perforated plastic films. How do they perform comparatively? vapor permeability, wind resistance, resistance to UV, longevity, etc.

The reason I'm asking, I recently ran across a partial roll of Tyvek in the attic rafters of my garage attic that was about 20 years old. It had visibly degraded and could be easily pulled apart. No UV, no wind wear, just age. What gives? And how long should it last underneath siding?

thanks. Jim

Asked by Jim Baerg
Posted Apr 27, 2018 4:57 PM ET


1 Answer

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Most reports of Tyvek deterioration involve either exposure to ultraviolet light (sunlight) for too many months, or contact with damp cedar siding (which contains tannins that reportedly degraded early versions of Tyvek).

DuPont, the manufacturer of Tyvek, claims that the product was reformulated after the tannin-related deterioration problems of the 1980s and 1990s were widely publicized. DuPont says that the newly reformulated Tyvek is resistant to extractives from cedar siding.

I certainly wouldn't use a roll of decades-old Tyvek I discovered in an attic. But I wouldn't worry too much about deterioration if (a) the Tyvek is new, and (b) the Tyvek is installed as part of a rainscreen system. (The air gap helps separate the Tyvek from liquids that may contain tannins that could attack the integrity of the plastic.)

Alex Wilson wrote a blog for GBA explaining why he chose a European water-resistive barrier (WRB) instead of Tyvek. Here is the link: What’s New with Water-Resistive Barriers.

Some traditionalists praise the longevity of asphalt felt -- especially #30 asphalt felt, which is thicker than #15 asphalt felt. Using asphalt felt as a WRB is one viable option.

Answered by Martin Holladay
Posted Apr 28, 2018 6:11 AM ET

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